Removing aperture-induced artifacts from fourier transform infrared intensity values

Abstract

Two Fourier transform infrared intensity artifacts have been observed at moderately high (0.1 cm^-1) spectral resolution: Light reflected off the aperture was double modulated by the interferometer, producing a 2f alias, and the warm (≈310 K) annulus of the aperture seen by a cooled detector resulted in distorted line shapes and anomalous intensities in the fingerprint region. Although the second artifact has been alluded to previously, we report corrections to remove both of these anomalies and to demonstrate the efficacy of these corrections. Prior to correction, integrated-band intensities were found to be in error by up to 12%.